4.6 Article

Highly modulated dual semimetal and semiconducting γ-GeSe with strain engineering

期刊

2D MATERIALS
卷 9, 期 4, 页码 -

出版社

IOP Publishing Ltd
DOI: 10.1088/2053-1583/ac83d5

关键词

gamma-GeSe; isotropic elastic properties; strain effect; indirect-direct bandgap transition

资金

  1. 100 Talents Program of Sun Yat-sen University [76220-18841201]
  2. Guangdong Basic and Applied Basic Research Foundation [2021B1515120025]
  3. National Natural Science Foundation of China [22022309]
  4. Natural Science Foundation of Guangdong Province, China [2021A1515010024]
  5. University of Macau [SRG2019-00179-IAPME, MYRG2020-00075-IAPME]
  6. Science and Technology Development Fund from Macau SAR [FDCT-0163/2019/A3]

向作者/读者索取更多资源

Layered hexagonal gamma-GeSe exhibits thickness-dependent conductivity, transitioning from semimetal to semiconductor. It also demonstrates superior flexibility and light absorption, making it promising for nanoelectronics and solar cell applications.
Layered hexagonal gamma-GeSe, a new polymorph of germanium selenide (GeSe) synthesized recently, shows strikingly high electronic conductivity in its bulk form (even higher than graphite) while semiconducting in the case of monolayer (1L). In this work, by using first-principles calculations, we demonstrate that, different from its orthorhombic phases of GeSe, the gamma-GeSe shows a small spatial anisotropic dependence and a strikingly thickness-dependent behavior with transition from semimetal (bulk, 0.04 eV) to semiconductor (1L, 0.99 eV), and this dual conducting characteristic realized simply with thickness control in gamma-GeSe has not been found in other two-dimensional materials before. The lacking of d-orbital allows charge carrier with small effective mass (0.16 m(0) for electron and 0.23 m(0) for hole) which is comparable to phosphorene. Meanwhile, 1L gamma-GeSe shows a superior flexibility with Young's modulus of 86.59 N m(-1), only one-quarter of that of graphene and three-quarters of that of MoS2, and Poisson's ratio of 0.26, suggesting a highly flexible lattice. Interestingly, 1L gamma-GeSe shows an in-plane isotropic elastic modulus inherent with hexagonal symmetry while an anisotropic in-plane effective mass owing to shifted valleys around the band edges. We demonstrate the feasibility of strain engineering in inducing indirect-direct and semiconductor-metal transitions resulting from competing bands at the band edges. Our work shows that the free 1L gamma-GeSe shows a strong light absorption (similar to 106 cm(-1)) and an indirect bandgap with rich valleys at band edges, enabling high carrier concentration and a low rate of direct electron-hole recombination which would be promising for nanoelectronics and solar cell applications.

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